The broad, long-term objective of this work is to obtain a better understanding of a novel mechanism of microorganism transmission. The central hypothesis is that a viral URI (rhinovirus infection) will cause nasal carriers of Staphylococcus aureus to have airborne dispersal of S.aureus secondary to nasal mucosal swelling with resultant more rapid airflow over wet surfaces. Experiments in specific Aim 1 will define the natural history of rhinovirus-associated airborne dispersal of S.aureus and whether airborne dispersal in this setting is further increased by nose breathing, coughing, or sneezing. The relationship between nasal mucosal swelling and rhinovirus infection will be evaluated using CAT scans, rhinomanometry, and acoustic rhinometry. A second important focus will be to determine the relationship between the number of S.aureus in the nose and airborne dispersal. Experiments in specific Aim 2 will be concerned with better defining the mechanism of rhinovirus-associated airborne dispersal of S.aureus. A topical decongestant will be used to test the hypothesis that reducing rhinovirus-associated mucosal swelling will prevent airborne dispersal. Stopping the medications of S.aureus nasally colonized allergic rhinitis patients will be used to evaluate whether just mucosal swelling is necessary or whether it takes mucosal swelling plus the rhinovirus. The quantitative relationship between the number of S.aureus in the nose and airborne dispersal will be tested by using tetracycline treatment to increase the number of tetracycline-resistant S.aureus in the nose and using topical mupirocin to reduce the number of S.aureus in the nose. Specific Aim 3 will determine the prevalence of single nasal S.aureus carrier-associated outbreaks, as well as identify individuals who may be studied to identify what properties make such individuals unique. S.aureus is the most important cause of nosocomial infections in the United States. S.aureus outbreaks are extremely disruptive and cause significant patient morbidity and mortality. Both "cloud babies" and "cloud adults", newborn infants or healthcare workers nasally colonized with S.aureus that airborne disperse S.aureus associated with a viral URI, have been shown to cause outbreaks. Understanding the "cloud phenomenon" may facilitate S.aureus outbreak prevention and possibly the transmission of other pathogens, as well.